“Is low digit ratio linked with late menarche? Evidence from the BBC internet study,” Manning JT, Fink B, Am J Hum Biol. 2011 May 5. The authors explain: “The ratio of the second and fourth digits (2D:4D) [etc.]… In a sample of 19 countries, mean right 2D:4D was negatively correlated with mean national AAM. These findings suggest that women with high prenatal testosterone and low prenatal estrogen tend to show late menarche and slow pubertal development.”
“Low Digit Ratio 2D∶4D in Alcohol Dependent Patients,” Kornhuber J, Erhard G, Lenz B, Kraus T, Sperling W, Bayerlein K, Biermann T, Stoessel C, PLoS One. 2011;6(4):e19332. The authors explain: “The ratio of the lengths of the second and fourth finger (2D∶4D) [etc.]… [We see it as] a possible trait marker in identifying patients with alcohol dependency.